Tag: rigging hardware

Over the past few years, our forging operations in Chattanooga, Tennessee, have been working vigorously to improve product quality and deliveries. As you have seen with our In-Stock Guarantee, we remain committed to manufacturing the highest quality products in the market, stocking over 275 of our most popular chain and forged rigging attachment products and guaranteeing to ship them in 3 business days.

As part of this commitment to quality, we implemented some changes that resulted in even higher quality shackles. These changes include larger CM shackle markings and a new shackle pin design.

Enhanced Shackle Identification Markings

The forged identification markings on our CM shackles are now the largest and most user-friendly on the market. The lettering has draft and rounded edges for use with synthetics. Some of the benefits of the larger and more legible lettering are:

Old Shackle SizeNew Shackle Size

Improved operator safety by reducing the risk of users misreading or not being able to read important size and WLL information.

Reduction in replacement costs by decreasing necessary out-of-service issues due to worn and illegible identification.

Easier identification of the product as a CM shackle with a larger CM logo forged into the side.

Old Shackle LogoNew Shackle Logo

New Pins

We have also changed the shackle pins on our Screw Pin Anchor shackles (SPA) to provide more efficient thread fitting inside and outside of the shackle.

New High Strength Pin

Both the enhanced ID markings and the new pins are now on all shackles we ship today. We will continue to look for even more ways to improve the safety and durability of our shackles, to ensure we are providing the highest quality products to our customers.

This article was originally posted on June 13, 2013. Updates were made on April 6, 2017 to keep our information current.

This question, “Forging vs. Casting: Which is better?” is one that I have been asked many times. To properly explore the answer, let’s first consider the process of each.

Forging and casting are two very different manufacturing methods. When something is cast the material is heated above its melting temperature and poured into a mold where it solidifies. When something is forged it is physically forced into shape while remaining in a solid state – although it is frequently heated.

As an engineer, I have always known that forgings normally have less surface porosity, finer grain structure, higher tensile strength, better fatigue life/strength, and greater ductility than castings. In other words, forgings are generally better for shackles. The basics of why are pretty simple. When you melt metal to cast it, the grain size is free to expand. When it cools back to a solid, the grain structure is courser and more random, decreasing its strength.

But just how much better is a forging than a casting?

I did some research on the internet and found an excellent research paper* written by members of the Industrial & Manufacturing Engineering Department at the University of Toledo, shared by the Forging Industry Association. This paper compares a single type of product made both ways. Read it here.

How’s this for hard numbers? No pun intended.

Based on this paper:

Forged parts had a 26% higher tensile strength than the cast parts. This means you can have stronger shackles at a lower part weight.

Forged parts have a 37% higher fatigue strength resulting in a factor of six longer fatigue life. This means that a forged shackle is going to last longer.

Cast iron only has 66% of the yield strength of forged steel. Yield strength is an indicator of what load a shackle will hold before starting to deform.

The forged parts had a 58% reduction in area when pulled to failure. The cast parts only had a 6% reduction in area. That means there would be much greater deformation before failure in a forged part.

To further illustrate the point, look at these photos from our in-house testing:

These forged CM shackles show significant deformities before failure.

If you were hanging a load overhead from a shackle, wouldn’t you want that shackle to warn you before it failed? Or do you like surprises?

Fortunately, all of our CM shackles are forged; and they’re forged right here in America at our Chattanooga, Tennessee Operations. Safer and made in America? I think that I will stick to forgings. What will you do?

* The title of the research paper is “Fatigue Performance Comparison and Life Predictions of Forged Steel & Ductile Cast Iron Crankshafts” written by Jonathan Williams, Farzin Montazersadgh, and Ali Fatemi, Graduate Assistants and Professor, respectively, Mechanical, Industrial & Manufacturing Engineering Department, The University Of Toledo – Toledo, Ohio.

History has proven the American-Made CM Super Strong Shackle is one of the most popular shackles on the market. Here are the top 5 reasons I think that’s true:

1. It’s Super Strong
That’s an obvious one, right? But in many cases, by using the Super Strong Shackle, you can use a smaller size shackle while maintaining the required strength and ductility. Our Super Strong Shackles are carbon type shackles which average 17%-50% greater strength than a comparable shackle. As a result of this strength, these shackles have a 6:1 design factor.

3. Proud to be Compliant with the “Buy American Act”Our chain and rigging attachments are made in the great state of Tennessee, USA. In accordance with the Buy American Act, we can provide you a Certificate of Compliance at your request. Learn more about the Buy American Act.

4. Meets RRC-271 Specifications
The Super Strong Shackle has to be de-rated to meet the specification of RRC- 271. What does this mean? The Super Strong Shackle has the same dimension of the standard carbon shackle that meets RRC 271, however, it’s much stronger. For example, a 1” CM Super Strong Shackle has a WLL of 10 ton, but RRC 271 requirements are 8-1/2. Because they exceed the requirements and are marked with higher strengths, the Super Strong Shackles cannot be represented as meeting RRC 271.

5. It’s In-Stock. We Guarantee It!Columbus McKinnon is committed and prepared to ship our most popular chain and forged attachment products in 3 days – and we guarantee it! This is our In-Stock Guarantee (ISG). Currently, we offer more than 275 hoist, chain and rigging products that are guaranteed to be in stock and ready to ship.

Designed and forged in Chattanooga, Tennessee, CM Super Strong shackles are carbon-type shackles with strength ratings that are up to 50% stronger than comparable sized carbon shackles. As a result, they are designed with a 6:1 safety design factor.

By using a special blended material, Columbus McKinnon is able to manufacture Super Strong shackles without requiring the quench and temper process. This gives our Super Strong shackles a higher working load limit (WLL) and greater design factor.

Our microalloy material is designed to be air cooled from normal forging temperatures. This air-cooling process eliminates the potential for errors in hardness and strength or quench cracks in the heat treating process.

The strength level of the microalloy forgings will be higher than the normal strength to hardness correlation allowing for greater ductility before failure. The microalloy has the ability to distribute strain throughout the section more uniformly than conventional steels. At the same hardness the microalloy will be stronger.

Below are Comparison Testing results of CM Super Strong Shackles versus Standard Carbon Shackles. While all of the CM shackles performed above their ratings, the Super Strong shackle performance was superior.

Questions often arise about the difference between our Industrial/Government shackles and the Super Strongshackles. An Industrial/Government shackle is a Super Strong shackle de-rated to meet – not exceed – the Federal Specification RR-C-271. That means it has the same dimensions and performance characteristics as a Super Strong shackle but is stamped with specifications to meet government requirements.

But don’t just listen to us. Listen to an impartial opinion and see the results of a test performed by Arizona Wire Rope. This distributor tested on a Tonzilla 500,000 lb pull tester comparing the CM Super Strong shackle to our competitor’s shackle. Check out the results for yourself!

Have you ever rigged a bundled load only to have that load spill out once your sling went slack? The solution is the CM Bundling Clip, which prevents the choker from going slack and the load from spreading after being unhooked. It also eliminates shear points and damage to wire rope. Check out our latest video and see the application for yourself.

Our new Bundling Clip is built for the harsh environments and demanding applications of the oil and gas industry as well as for rail yards, logging, construction applications or wherever you are lifting, storing or moving cylindrical material.

S. H. from Georgia writes:

I am unfamiliar with the standards governing shackles and have a question regarding the stamped WLL on your shackles. Our company is using shackles with different ratings on them. For example, we use a ½” shackle stamped a 2T WLL and a ½” shackle stamped with a 3T WLL. I understand that there was a change in the standard several years ago and wonder if you could recommend which load rating is the correct one and what should be done with the shackles with incorrect stamping. Also, neither shackle is stamped or marked as High Strength “HS” as required by the standard RR-C-271D and Amendment 1. Any information that you can provide would be appreciated.

Both of the WLL stamps on your two types of shackles may be correct. Shackles fall under ASME B30.26 rigging hardware. Shackle working load limits differ based on materials used to construct the shackle. The industry has three types of materials for shackles: Carbon, Super Carbon and Alloy. This means that you can have three shackles of all the same size (diameter) and have three very different working load limits. ASME B30.26 requires the working load limit be stamped on all shackles. A rigger must look for the WLL stamped on the shackle.

This is why you must never base your working load limit by diameter. If the WLL is no longer legible, the shackle should be discarded.

The classification of a shackle as “High Strength” is based upon the classification of the shackle pin as HS. The HS stamp will be on the pin or bolt, not on the shackle. All CMCO shackles – carbon, super carbon or alloy – have HS pins. So, you do not need to worry about mixing up pins between carbon, super carbon and alloy when using CMCO products.